1. Field of the Invention
The subject invention generally pertains to a carwash and more specifically to a system for controlling the path of a spray arch.
2. Description of Related Art
To wash a vehicle in what is known as a touchless automatic carwash, the vehicle is usually parked at a desired location within a wash bay. Once a tire-engaging treadle switch or some other sensor system determines that the vehicle is properly parked, a controller commands an overhead supporting structure to move one or more spray arches (or some other type of pipe with a series of spray nozzles) around the vehicle to sequentially spray various mixtures of water, soap, and other chemicals at a temperature and pressure sufficient to flush dirt and grime off the vehicle.
To maintain a desired spraying distance between the spray arch and the vehicle, the controller typically guides the movement of the arch in response to multiple additional sensors that determine the positions of the vehicle's exterior surfaces, such as the vehicle's front, back, right side, and/or left side. Examples of carwash systems that employ multiple sensors are disclosed in U.S. Pat. Nos. 6,425,407; 6,769,440 and 6,551,415
The various sensors of a carwash can be problematic due to the harsh environment in which they operate. Fog, water spray, dirt, strong chemicals, and ice are just a few of the common elements that can disrupt the operation of sensors. Many sensors may provide false signals due to vehicles of widely varying design where the exterior surface of the vehicle may vary by color, shape, material (e.g., plastic, metal, glass), reflectivity, height, angle, etc.
Consequently, there is a need for a system that can reliably control the path of a spray arch with a minimal number of sensors.